A fuel supply system which supplies fuel to an engine is equipped with a high-pressure pump which pressurizes the fuel suctioned from a fuel tank. A high-pressure pump has a plunger which pressurizes the fuel introduced into a pump chamber through a fuel inlet and a fuel supply passage. The pressurized fuel is discharged through a fuel outlet.
JP-2001-304068A shows a high-pressure pump having a needle valve fixed to a movable core. The needle valve sits on or moves apart from a valve seat to close or open the fuel supply passage. The needle valve is supported by a needle guide which is arranged between a movable core chamber and the fuel supply passage. The needle guide has a communication hole which fluidly connects the movable core chamber and the fuel supply passage. Thereby, a movable core chamber functions as a damper chamber, so that a noise due to a collision between the needle valve and the valve seat can be reduced.
In the above high-pressure pump, as an opening sectional area of the communication hole is made larger, a flow resistance of the fuel flowing through the communication hole becomes smaller and the operation and a movement of the movable core become quicker.
Thus, in a suction stroke of the high-pressure pump, after the movable core and the needle valve collide with a stopper by a biasing force of a spring, it is likely that the movable core and the needle valve may bounce toward a fixed core. At this moment, when the movable core and the needle valve are magnetically attracted to the fixed core in a metering stroke, a valve-close time of the needle valve is made earlier, so that a discharging stroke starts earlier than an intended time. Even if an energization start time of a coil is made later, the fuel discharge quantity is increased. It may be difficult to control the fuel discharge quantity with high accuracy.